package com.geniu.concurrent;

import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveTask;

/**
 * fork join 模式计算 斐波那契数列
 */
public class ForkJoinTestDemo {


	public static void main(String[] args) {
		//创建分治任务线程池
		ForkJoinPool fjp = new ForkJoinPool(4);
		//创建分治任务
		Fibonacci fib = new Fibonacci(30);
		//启动分治任务
		Integer result = fjp.invoke(fib);
		//输出结果
		System.out.println(result);
	}

	//递归任务
	static class Fibonacci extends RecursiveTask<Integer> {
		final int n;
		Fibonacci(int n) {
			this.n = n;
		}
		@Override
		protected Integer compute() {
			if (n <= 1) {
				return n;
			}
			Fibonacci f1 = new Fibonacci(n - 1);
			//创建子任务
			f1.fork();
			Fibonacci f2 = new Fibonacci(n - 2);
			//等待子任务结果，并合并结果
			return f2.compute() + f1.join();
		}
	}
}
